1. Field of the Invention
The present invention relates to an image forming apparatus such as a printer, a facsimile apparatus, or a copying machine and, more particularly, to an image forming apparatus having a main body to which an optional sheet feeding device is detachably connectable.
2. Description of the Related Art
In recent years, the performance of image forming apparatuses such as printers, facsimile apparatuses and copying machines have been improved to cope with the demand for higher processing speed. This leads to a demand for the use of sheet stack cassettes and ejected sheet trays having greater capacities. Image forming apparatuses capable of bulk handling are designed to allow optional sheet feeding devices of large capacities to be connected thereto upon requests of users.
FIG. 18 shows one such image forming apparatus, by way of example. This image forming apparatus has a main body 101 having an image forming section 102, and a sheet feeding device 131 arranged under the main body 101. During operation of the image forming apparatus, a sheet fed by a sheet conveyor unit 132 provided in the sheet feeding device 131 is received by a sheet conveyor unit 103 provided in the main body 101 of the image forming apparatus, and is conveyed by this unit into an image forming section 102 of the image forming apparatus.
This conventional image forming apparatus requires the conveying unit 103 for conveying the sheet fed from an option sheet feeding device 131 into an image forming section 102. It is necessary that actuating means including a motor and an electromagnetic clutch for actuating the conveying unit 103 be installed in the main body of the image forming apparatus, for conveying the sheet fed from the optional sheet feeding device.
Provision for such a motor or electromagnetic clutch requires that a power supply unit installed in the image forming apparatus has a capacity large enough to accommodate power for activating such motor and clutch. Consequently, the structure of the apparatus main body is complicated and the cost of production of the same is raised. Such additional costs, however, does not offer any particular advantage to the users who do not use optional sheet feeding devices.
Accordingly, it is an object of the present invention to provide an image forming apparatus which is improved to simplify the structure and which can reduce the production cost, while allowing connection thereto of an optional sheet feeding devices.
To this end, according to the present invention, there is provided an image forming apparatus which has: a main body with an image forming section, an optional sheet supply means connectable to the main body, for feeding sheets into the main body, and a sheet conveyor unit demountably mounted in the main body, for receiving, when the sheet supply means is connected to the main body, a sheet fed from the sheet supply means and for conveying the sheet toward the image forming section.
In accordance with yet another object of the present invention there is provided the above-described image forming apparatus, together with a driving power source in the sheet supply means and a driving power transmission means for transmitting driving power from the driving power source in the sheet supply means to the sheet conveying unit mounted in the main body.
In accordance with yet another object of the present invention there is provided an image forming apparatus which has a main body with an image forming section, an optional sheet supply means connectable to the main body, for feeding sheets into the main body, and a sheet conveyor unit demountably mounted in the main body, for receiving, when the sheet supply means is connected to the main body, a sheet fed from the sheet supply means and for conveying the sheet toward the image forming section, wherein a driving power source mounted in the main body and a driving power transmission means for transmitting power from the driving power source to the sheet conveyor unit is mounted in the main body.
In accordance with yet another aspect of the present invention there is provided an image forming apparatus as described above, together with a sheet conveyor means provided in the sheet supply means for conveying the sheets from the sheet supply means into the main body and extension driving power transmission means for transmitting the power derived from the driving power source to the sheet conveyor means.
In accordance with still yet another aspect of the present invention there is provided a sheet conveyor unit for guiding a sheet to an image forming section of an image forming apparatus, the sheet being received from an optional sheet supply means connected to the image forming apparatus. The sheet conveyor unit is comprised of a frame mountable in the image forming apparatus, the frame, when mounted, providing a vertical conveyor path along which the sheet received from the optional sheet supply means is fed upward, a conveyor means provided on the frame for conveying the sheet received from the optional sheet deck and a guide provided on the frame, also for guiding the sheet received from the optional sheet supply means.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.